Graphene transport at high carrier densities using a polymer electrolyte gate

We report the study of graphene devices in Hall-bar geometry, gated with a polymer electrolyte. High densities of 6 x 10(13)/cm(2) are consistently reached, significantly higher than with conventional back-gating. The mobility follows an inverse dependence on density, which can be correlated to a dominant scattering from weak scatterers. Furthermore, our measurements show a Bloch-Gruneisen regime until 100K (at 6.2 x 10(13)/cm(2)), consistent with an increase of the density. Ubiquitous in our experiments is a small upturn in resistivity around 3 x 10(13)/cm(2), whose origin is discussed. We identify two potential causes for the upturn: the renormalization of Fermi velocity and an electrochemically enhanced scattering rate. Copyright (C) EPLA, 2010